The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
The Calculation of the mass fraction burned for an internal combustion engine is an indicator of the rate that heat is release as the charge burns in a specific cylinder event. The results of this calculation can be used as an indication of combustion phasing, rate of heat release, charge dilution, or other metrics used in the control of an internal combustion engine. The determination of mass fraction burned may be used for controlling different engine functions. There are alternative methods to calculate mass fraction burned in an internal combustion engine. Those methods are either computationally complex or have insufficient accuracy for the engine control purposes. The Rassweiler-Withrow method is one of the most efficient equations, providing a very accurate representation of charge heat release. There are more accurate equations, but they are very computationally expensive. However, the formula involves an exponential term whose power is varying at each engine cycle. Since this exponential term should be calculated repeatedly throughout one engine cycle, it is a computationally expensive operation for real-time implementation.